The present invention relates to a new fluorinated tetraphenyl derivative, a new blue light-emitting polymer prepared using the tetraphenyl derivative as a monomer, an electroluminescence (EL) device manufactured using the polymer and a method for preparing or manufacturing the same. More particularly, the new fluorinated tetraphenyl derivative of the invention is represented as the formula (I) and allows the polymers prepared from it to be excellent in the ability of electron injection and transportation. The light-emitting polymer of the invention is represented as the formula (II) and is prepared by the reaction of the fluorinated tetraphenyl derivative with the compound allowing the polymer to be excellent in the ability of hole injection and transportation. The EL, device of the invention is manufactured using the light-emitting polymer. 
Here, A is xe2x80x94P(OR)2 or xe2x80x94P+Rxe2x80x23, wherein R and Rxe2x80x2 is an alkyl group or an aryl group. 
Here, xe2x80x94Arxe2x80x94 is an arylene group.
Generally, as shown in FIG. 1, an EL device is formed by depositing, in turn, a transparent electrode 2, a hole transport layer 3, a polymer light-emitting layer and a metal electrode 6 on a substrate 1. When the transparent electrode 2 and the metal electrode 6 are respectively connected to the (+) terminal and (xe2x88x92) terminal of a power supplier and power is supplied, holes are supplied to the polymer layer 4 through the transparent electrode 2 and hole transport layer 3, electrons are also supplied to the polymer layer 4 through the metal electrode 6 and the electron transport layer 5, and thereby, the holes and the electrons are combined in the polymer layer 4 to result in light emission.
Up to now, generally, xcfx80-conjugated polymers such as poly(1,4-phenylenevinylene) (PPV), poly(para-phenylene) (PPP) and polythiophene (PT) are mainly used as light-emitting materials of polymer electroluminescence (EL) devices. Such a xcfx80-conjugated polymer is excellent in the abilities of hole injection from the anode and the transport for the injected hole, but is not good in the abilities of electron injection from the cathode and the transport for the injected electron.
The majority of the holes injected from the anode could not combine with the electrons injected from the cathode, which flow to the cathode. Therefore, the light emission efficiency of the EL device using the above polymer material as the emitting layer is very low, for the low combination probability of the holes with electrons.
For example, U.S. Pat. No. 5,247,190 discloses conductive polymers, poly(1,4-phenylenevinylene) and its derivatives as a light-emitting material.
U.S. Pat. No. 5,514,878 also discloses a method for enhancing the efficiency of a light-emitting device. In the patent document, the light-emitting device is manufactured using a light-emitting polymer containing a high electron affinity group, cyanide (CN) group and electrons are easily injected from the metal electrode (cathode) in the device, thereby, the combination probability of hole with electron is enhanced.
U.S. Pat. No. 5,376,456 also discloses a copolymer comprised of phenylenevinylene units and two benzene group containing units, wherein the benzene group is substituted with trifluoromethyl group.
However, the devices as described above are mostly not good in the electron injection and transport ability and thus, the holes injected from the anode flow to the cathode without combination with the electrons, that is, the combination probability of hole with electron is not sufficient.
Therefore, the device of the prior art is not sufficient in the light emission efficiency.
It is, therefore, an object of the present invention to provide fluorinated tetraphenyl derivatives and methods for preparing the same. Wherein the tetraphenyl derivative can be used as a monomer to prepare the light-emitting polymer excellent in electron injection and transport ability.
It is another object of the present invention to provide light-emitting polymers, with which the EL devices are excellent in electron injection and transport ability as well as in hole injection and transport ability and are light-emittable in the blue emission region, in which the EL device with inorganic material is not light-emittable. The light-emitting polymer of the invention is an alternated copolymer having, in alternated order, repeated units excellent in hole injection and transport ability and repeated units excellent in electron injection and transport ability. The present invention also provides methods for preparing the polymers.
It is also another object of the present invention to provide an EL device which is excellent in electron injection and transport ability as well as in hole injection and transport ability and is light-emittable in the blue emission region. The EL device of the invention is manufactured using the light-emitting polymer.
In accordance with one embodiment of the present invention, there are provided fluorinated tetraphenyl derivatives which are represented as the following formula (I). 
Here, A is xe2x80x94P(OR)2 or xe2x80x94P+Rxe2x80x23, wherein R and Rxe2x80x2 is an alkyl group or an aryl group. Preferably, A is xe2x80x94P(OCH2CH3)2 or xe2x80x94P+(C6H5)3.
In accordance with another embodiment of the present invention, there are provided light-emitting polymers which are represented as the following formula (II). 
Here, xe2x80x94Arxe2x80x94 is an arylene group. Preferably, xe2x80x94Arxe2x80x94 is selected from a group consisting of 
wherein R, R4, R5, R6 and R7 are each selected from hydrogen or linear or branched alkyl group having 1-20 carbons, and R2 and R3 are each selected from hydrogen or linear or branched alkyl or alkoxy group having 1-20 carbons.
In accordance with another embodiment of the present invention, there are provided EL devices containing a polymer light-emitting layer formed with the light-emitting polymer.